The invention relates to a coil former.
In coils from the field of electrical engineering, arranging the actual coil winding on an insulating material part, which is referred to as the coil former, is known. Such a coil former assists the winding procedure in that it helps, for example, the positioning of the individual windings of the coil winding and helps the intended shape of the coil to be maintained more exactly. Furthermore, the coil former electrically insulates the coil winding, in the case of coils which are arranged on a magnetic core or simple core, at least regionally in relation to the core, and during the winding of the coil winding protects the core from the mechanical stresses, which can result in worsening of the magnetic properties of the core.
Of course, cavities between the coil winding and the core and/or the coil former may hardly be avoided. These worsen the heat transfer from the coil winding into the core and represent a limiting factor with respect to the permissible power loss of the coil assembly. Filling these intermediate spaces using a curable potting compound is therefore furthermore known. This often takes place in the scope of a so-called trickle process, in which the otherwise finished coil assembly is arranged such that a part of the outermost winding layer is directly accessible from above. Liquid potting compound is subsequently applied drop by drop onto this outermost winding layer. The distribution of the potting compound through the coil winding takes place due to capillary action and gravity.
In order to fill as many intermediate spaces as possible in such a process, it is carried out until the potting compound drips off again already at the lower end of the coil assembly, and also an appropriately thin and/or low-viscosity potting compound is selected. It is disadvantageous that the process of trickling is very time-consuming and dirty. The trickling itself is already time-consuming, since only small quantities of the potting compound can be applied at a time, and therefore it is necessary to wait between each two drops. Since the intermediate spaces of the coil winding are to be filled as completely as possible by the potting compound, a potting compound has to be selected which has a long curing time and low viscosity, in order to assist the most complete possible penetration of the coil winding. This has the result that all coil assemblies have to be set aside over a longer period of time after the filling of the coil winding, in order to enable drying of the potting compound. Moreover, the circumstance that trickling has to be performed until the potting compound drips out or from the coil again has the result that the region in which this process step takes place is soiled by the dripping potting compound. Therefore, separate areas are required for the trickle process and also the subsequently required drying.
Alternatively thereto, a higher-viscosity potting compound can also be selected, whereby it is possible to avoid dripping potting compound soiling the work environment. However, such a potting compound does not penetrate all cavities, whereby there are regions of the coil in which no potting compound is arranged, with the corresponding disadvantages with respect to the heat dissipation.
The viscosity of the potting compound is dependent in this case in a manner known per se on the processing temperature.